IT IS the superfood Guy Leech credits with saving his health and helping him regain his peak physical fitness.

Now the former Ironman wants to show how one tiny food can make such a difference even in the super fit.

As a professional athlete and former Ironman, Leech already had a diet most fitness fanatics would only dream about.

Filled with lean meat, plenty of fruit, vegetables, wholegrains and limited alcohol intake, the father-of-two was living the healthy life.

But when he developed a major gut problem a year ago, his training and health began to suffer so badly he had days where he was unable to function.

"I had days where I literally couldn't get out of bed and I couldn't work out was wrong," he said.

"I went to every health practitioner under the sun and eventually found I had a parasite in my gut which was feeding off the high-fat dairy products I was eating."

Despite medication and various foods, nothing seemed to work or fix the problem which "floored" him.

But then he stumbled upon a superfood, BARLEYmax, which began to starve and eventually kill the parasite he had picked up while travelling through Thailand and Indonesia.

The super grain developed by the CSIRO is a non-genetically modified wholegrain which contains twice the dietary fibre of regular grains and has a low GI.

The 49-year-old not only credits the superfood with saving his health, but eats it daily for breakfast, sometimes even having two serves a day.

"I was sick of feeling rotten, so thought I'd try this superfood," he said.

Within a month, he was back on track and training every day and was so impressed with his new diet find, he approached Goodness Superfoods to become an ambassador.

Admitting it sounded weird for him to approach a company, instead of the other way around, Leech said he wanted to show how one simple change could make such a big difference.

Now back on track, the Australian Ironman surf lifesaving champion still trains up to one-and-a-half hours each day and leads regular group fitness sessions.

And while his health scare may have been a setback, Leech reckons it has simply forced him to go from healthy to super healthy in a short time.

But the World Diabetes Day and Goodness Superfoods ambassador admits even he isn't that strict when it comes to enjoying a treat.

The fitness fanatic pictured in the water back in 2002. Picture: Greg PorteousSource:Supplied

He says he lives by the 80-20 diet, which is to eat well 80 per cent of the time, and somewhere between 'okay' and 'not so excellent' the other 20 per cent.

The fitness guru also eats lean meat, salads, vegetables and plenty of other grains, and limits his alcohol intake.

Ahead of World Diabetes Day tomorrow, Leech said it was a concern that more Australians were becoming obese and the illness was on the increase.

He also said it was vital people became more concerned with what they put into their bodies.

"When I was 12, my dad had a heart attack in front of me," he said.

"As someone who has always had sport and fitness play a big role in my life, I wanted to try to pass on that knowledge and experience to other people. That's what motivates me.

"Better choices will set you free."

So what does a former Ironman eat then? Here are his tips for staying in shape.

• Eat lots of grains, which are low in GI, and keep you full for longer;

• Eat until you're satisfied and if you're still hungry wait five minutes to eat more. According to Leech we have become a nation of over-eaters and reducing portions by five per cent a day for a week will make a big difference to your waistline;

• Have a diet that encompasses the five food groups;

• Don't beat yourself up for having a treat;

• Limit alcohol intake, not only is it a toxin but it is stored in the body as fat;

• Have lots of lean meat, fresh fruit and vegetables, carbs and water;

• Avoid too many preservatives - if you've had something in your cupboard for months and it's still in date chances are it's not the best food option for you;

• Exercise as much as you can, even if it's a short walk each day;

• Limit high-fat dairy foods which can be hard to digest

Maintaining a fit and healthy lifestyle is vital for the father-of-two. Picture: Greg PorteousSource:Supplied

The Goodness Superfoods ambassador with the one food he eats each day.Source:Supplied